1. Field of the Invention
This invention relates, in general, to preparing sheets of material for bending using punching, stamping, roll-forming, and similar processes and then bending the sheets into three-dimensional structures.
2. Description of Related Art
Various methods of preparing sheet materials for precision folding along a desired bend line have been developed. For example, U.S. Pat. Nos. 6,877,349, 6,877,349, 7,032,426, 7,152,449 and 7,152,450 describe various methods of preparing and folding sheet materials for forming three-dimensional objects having relatively high tolerances from substantially planar two-dimensional sheets.
The folding-structures shown and described above promote so-called edge-to-face engagement and other phenomena to facilitate folding along a desired bending line. For example, as discussed in the above-mentioned '450 patent, displacements may be formed to facilitate bending along a desired bend line. In some instances, gaps may be formed between a sheared edge of a displacement and an opposing face of the bent sheet material. For example, the gaps may be designed into the bend-controlling structures to further facilitate bending. As another example, the gaps may result from an engineered design to provide clearance during bending or lower manufacturing tolerances. In yet another example, the gaps may be undesired, and may have resulted from various factors.
The presence of such gaps along the folded edges may present problems. As noted in the above-mentioned '449 patent, certain flat sheets that are slit or grooved can have electrical components mounted to them using “pick-and-place” techniques. The sheets may then be folded into enclosures or housings in which all of the components are spatially related in the desired positions inside the housing. While there is considerable advantage to slit-forming or groove-forming techniques, in applications where shielding is important, gaps along the enclosure edges may lead to electromagnetic (“EM”) waves or radio-frequency (“RF”) signal noise leakage out of the structure.
Additionally, the presence of gaps or pockets along the bend lines may, in some instances, reduce the strength of the folded structure. For example, because the gaps decrease the surface contact between edge and face, the folded structure may have less surface area to support loading. In such cases, it may be desirable to increase the structural integrity of the folded product in the gap regions.
In addition, traditional manufacturing techniques often require the use of various fasteners to hold panels of a sheet material in a folded 3D structure.
It would therefore be useful to provide a sheet of material having bend-controlling structures that facilitate precise bending techniques, reduce the gap area near the bend lines, and/or include securing structures that may reduce the need for fasteners in securing a 2D sheet material into a 3D structure.